Examination Of The Molecular Pharmacology Of Anthracyclines Induced Via Their Interaction With Iron
Funder
National Health and Medical Research Council
Funding Amount
$618,401.00
Summary
Anthracyclines are highly effective anti-cancer drugs, but their use is limited by toxic effects on the heart. This is thought to be due to these drugs directly binding iron (Fe). Indeed, we showed that anthracyclines induced marked changes in the way heart cells utilise Fe (DR1-3, 38; Mol. Pharmacol. 2002, 2003, 2004, 2005). We were the first to show that anthracyclines prevent Fe release from the criticial Fe storage protein ferritin. This prevents the use of Fe for vital processes eg. DNA and ....Anthracyclines are highly effective anti-cancer drugs, but their use is limited by toxic effects on the heart. This is thought to be due to these drugs directly binding iron (Fe). Indeed, we showed that anthracyclines induced marked changes in the way heart cells utilise Fe (DR1-3, 38; Mol. Pharmacol. 2002, 2003, 2004, 2005). We were the first to show that anthracyclines prevent Fe release from the criticial Fe storage protein ferritin. This prevents the use of Fe for vital processes eg. DNA and haem synthesis. Hence, this effect probably contributes to the cytotoxic activity of anthracyclines on the heart. We showed that novel drugs developed in my lab that bind Fe called chelators show high activity in animals (DR4) and prevent anthracycline-mediated Fe accumulation in ferritin. Importantly, Fe chelators have been shown to inhibit anthracycline-mediated cardiotoxicity. Indeed, the clinically used cardioprotective agent, ICRF-187, is actually an Fe chelator (5, DR6). However, ICRF-187 is not totally successful in terms of its cardioprotective effects and can cause myelosuppression (5, DR6). While the clinically used chelator, desferrioxamine (DFO), can prevent anthracycline-mediated cardiotoxicity, its poor membrane permeability limits its effectiveness. Our chelators are highly permeable and overcome the disadvantages of DFO (DR4). Thus, they are vital to examine for preventing anthracycline-mediated cardiotoxicity. In this proposal we will examine the changes in Fe metabolism induced by anthracyclines and test the hypothesis that novel Fe chelators may prevent the cardiotoxicity of these agents. We also aim to be the first to assess if preparation of anthracyclines which cannot bind iron prevents their cardiotoxicity. This will be done by preparing metal complexes of these drugs which prevent Fe-binding eg. anthracycline-zinc complexes. These studies are important for the development of less cardiotoxic forms of these very useful anti-tumour agents.Read moreRead less
Potential Anti-tumour Agents: Iron Chelators Of The Pyridoxal Isonicotinoyl Hydrazone Class
Funder
National Health and Medical Research Council
Funding Amount
$472,770.00
Summary
Iron (Fe) is essential for proliferation. Generally, cancer cells have a high Fe requirement due to their rapid rate of proliferation making them very susceptible to iron chelators which deplete cells of Fe. The potential of this therapy has been confirmed by the entrance of the chelator, Triapine (Vion Pharmaceuticals), into clinical trials. Further, a wide variety of studies including clinical trials have shown that the clinically used Fe chelator, desferrioxamine (DFO), can have potent anti-t ....Iron (Fe) is essential for proliferation. Generally, cancer cells have a high Fe requirement due to their rapid rate of proliferation making them very susceptible to iron chelators which deplete cells of Fe. The potential of this therapy has been confirmed by the entrance of the chelator, Triapine (Vion Pharmaceuticals), into clinical trials. Further, a wide variety of studies including clinical trials have shown that the clinically used Fe chelator, desferrioxamine (DFO), can have potent anti-tumour activity. Indeed, in an important clinical trial (Cancer Res 1990;50:4929), a marked decrease in tumour burden was observed while there was no significant side effects, demonstrating an appreciable therapeutic index. However, DFO suffers serious problems, including that it requires long infusions and does not readily permeate cells. Considering this, during the current NHMRC grant, we developed a novel group of chelators that show far greater activity than DFO and Triapine at inhibiting cancer growth in vitro and in vivo (Richardson BLOOD 2004;104:1450). These studies have been published in high quality journals such as BLOOD and Clin Cancer Res (Richardson 1995, 1997, 1999, 2001, 2002, 2004a,b,c) Recently, a potent metastasis suppressor gene, known as differentiation related gene-1 (Drg-1), has been identified. Up-regulation of this molecule plays an important role in inhibiting the growth of primary cancers and their metastatic spread. Importantly, we have recently shown that our new chelators markedly up-regulate the expression of Drg-1 in cancer cells and at the same time markedly and selectively inhibit the growth of these cells (Richardson BLOOD 2004;104:2967). Our hypothesis is the marked increase in Drg-1 expression after treatment with chelators could inhibit cancer cell growth and metastasis. Studies in this NHMRC grant renewal will lead to the development of new therapies and a greater understanding of cancer metastasis and biology.Read moreRead less